[nas] Re: Sound dropouts using ALSA and NAS on Linux

Charles Levert charles at comm.polymtl.ca
Thu Aug 24 16:56:29 MDT 2000

David Morano <morano at computer.org> writes:

> Charles wrote :

> > Indeed, programs such as mpg123 typically program NAS with a huge
> > playout buffering delay.  Moreover, using debugging output from the
> > server, I can see that once in a while, the kernel sends a SIGPOLL
> > late:

> Ya, a late SIGPOLL is a killer if that is all that is used to
> wait for the ability to write more data to the device.
> Has there ever been a server implementation where a separate thread
> just sits with blocking write(2)'s on the audio device ?
> Maybe something like that would be a way to get around depending on
> SIGPOLL arriving before the current data is all flushed out
> of the device.

Having to program directly with threads may involve changing other
parts of the NAS server, which may be problematic.  (I'm not sure, I
haven't given it enough thought yet.)  There may be another
possibility on SunOS: aiowrite(3) and aiowait(3).  I don't know how
these are implemented (since they are library functions, not system
calls) and how they would behave.


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